>>I seem to recall that having debugging enabled can cause this? Check the 'debug' attribute of the compilation tag in web.config.
>
>Debug is set to False. Here is the top of the Web.config file.
>
>

><?xml version="1.0"?>
><configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
>	<appSettings/>
>	<connectionStrings/>
>	<system.web>
>		<identity impersonate="true"/>
>		<compilation debug="false" targetFramework="4.0">
>

>
>So, I will have to do some research as to know what else could be in effect here.
>
>>You can also change the number of recompiles before a recycle - quick search indicates that it's the numRecompilesBeforeApprestart attribute in machine.config. But doing that would really just be avoiding the issue without knowing the cause.....
>
>I agree.

Two other, rather more obscure, possible causes I came across:
(a) Writing to any file in the bin directory (or any sub-folder thereof)
(b) Anti-virus software changing the datestamp of, for example, web.config......